Abstract: Aminopeptidase N (APN) is an enzyme that preferentially cleaves neutral amino acids from the amino-terminus of proteins or oligopeptides.This enzyme is widely distributed in the plants and animals.In insects,APN is most abundant in the brush border membrane of the midgut and is an enzyme involved in the digestion of protein in food and the toxication of Bt for target insects.The recent research results of APNs of insects in the world were summarized.The characteristics,configuration,classification,isolation and purification,relationship between the catalytic and toxin-binding sites,phylogenetic relationship,gene function,the distribution and gene expression level,the recent studying methods and results of APNs and whether they are related between the Bt resistance of insects and APNs were elucidated.It is necessary to further study the function of APNs in view of the effect of other receptors,action complication and limited research techniques.